Fennix/Kernel/Architecture/amd64/SystemCalls.cpp

93 lines
2.5 KiB
C++

/*
This file is part of Fennix Kernel.
Fennix Kernel is free software: you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation, either version 3 of
the License, or (at your option) any later version.
Fennix Kernel is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with Fennix Kernel. If not, see <https://www.gnu.org/licenses/>.
*/
#include <syscalls.hpp>
#include <cpu.hpp>
#include "cpu/gdt.hpp"
// https://supercip971.github.io/02-wingos-syscalls.html
using namespace CPU::x64;
// "Core/SystemCalls.cpp"
extern "C" uint64_t SystemCallsHandler(SyscallsFrame *regs);
extern "C" void SystemCallHandlerStub();
extern "C" __naked __used __no_stack_protector __aligned(16) void SystemCallHandlerStub()
{
asmv("swapgs\n"
"mov %rsp, %gs:0x8\n" // CPUData->TempStack
"mov %gs:0x0, %rsp\n" // CPUData->SystemCallStack
"push $0x1b\n" // user data segment
"push %gs:0x8\n" // saved stack
"push %r11\n" // saved rflags
"push $0x23\n" // user code segment
"push %rcx\n" // Current RIP
"push %rax\n"
"push %rbx\n"
"push %rcx\n"
"push %rdx\n"
"push %rsi\n"
"push %rdi\n"
"push %rbp\n"
"push %r8\n"
"push %r9\n"
"push %r10\n"
"push %r11\n"
"push %r12\n"
"push %r13\n"
"push %r14\n"
"push %r15\n"
"mov %rsp, %rdi\n"
"mov $0, %rbp\n"
"call SystemCallsHandler\n"
"pop %r15\n"
"pop %r14\n"
"pop %r13\n"
"pop %r12\n"
"pop %r11\n"
"pop %r10\n"
"pop %r9\n"
"pop %r8\n"
"pop %rbp\n"
"pop %rdi\n"
"pop %rsi\n"
"pop %rdx\n"
"pop %rcx\n"
"pop %rbx\n"
"mov %gs:0x8, %rsp\n" // CPUData->TempStack
"swapgs\n"
"sti\n"
"sysretq\n");
}
void InitializeSystemCalls()
{
wrmsr(MSR_EFER, rdmsr(MSR_EFER) | 1);
wrmsr(MSR_STAR, ((uint64_t)(GDT_KERNEL_CODE) << 32) | ((uint64_t)(GDT_KERNEL_DATA | 3) << 48));
wrmsr(MSR_LSTAR, (uint64_t)SystemCallHandlerStub);
wrmsr(MSR_SYSCALL_MASK, (uint64_t)(1 << 9));
}